Hydraulically operated apparatus



June 22, 1943. H. H. VANDERZEE 2,322,739

HYDRAULICALLY OPERATED APPARATUS I Filed Nov. 14, 1959 s Sheets-Sheet 1v June 22, 1943. VANDERZEE 2,322,739

HYDRAULICALLY OPERATED APPARATUS Filed Nov. 14, 1959 3 Sheets-Sheet 2[Elam or: any/5. Vail/2166.

vJune 22, 1943. I H, VANDERZEE 2,322,739

HYDRAULICALLY OPERATED APPARATUS Filed Nov 14; 19:59 5 Sheets-Sheet alzzyjar 16 175916. .1729. 12' W 36 7 1;

Patented June .22, 1 943 UNITED s'rik rus PATENT OFFICE I nmnaumcmjfiintzrnp nrraua'rus I 7 Harry B. Vanderlec, Michigan City, Ind.,

ass

or to Sullivan Machinery Company, a om. tion of Massachusetts I v 15Claims.

This invention relates to hydraulic pump systems, and more particularlyto improvements in the controlling means for a rotary drilling apparatusof the type embodying hydraulically operated feeding means and hydraulicoperating means forthe drill chuck. y

In drilling apparatus of the rotary core type, the drill bit is usuallyfed by hydraulic pressure toward and from the work. Inthe normaldrilling operation, the drill bit is fed toward the work rather slowlyand; as drilling progresses and the weight of the drill rods increases,apoint is finally reached when no hydraulic feeding force is necessary.and beyond this point the weight of the drill rods, in excess ofthepressure required to feed the drill bit to the work, must be removedfrom the bit, or an excessive feeding pressure on the bit will? result.Ordinarily. when the weight of the drill rods becomesexcessive, theexcess weight is removed from the -bit by hydraulic pressure. In otherwords. the. feeding pressure applied to the drillbit is determined bythe weight of thedrill rods. 'The hydraulic pressure in the hydraulicsystem must, be suflicient for lifting the weight of the drill rod linefor a hole of a given depth. .It is accordingly evident that the feedingpressure on the drill bit must be relatlvely high during starting of thedrill hole, and as the length of the rod line increases; the feedingpressure must be reduced, and when the ing apparatus wherein the volumeof liquid supplied, to the system may be varied in accordance with .thedemand. Yet another object is to provide a dual capacity pumparrangement embodying a pump unit of small capacity and a pump unit oflarge capacity, the pump of small capacity normally maintaining therequired; pressure in the fluid system when a small volume is required,and the pump of large capacity supplying a substantially greater volumeof of the small capacity pump eliminating the excessive generation ofheat in the fluid system which would occur if the large pump had toforce;

vention will, however, hereinafter more fully ap- I pea In theaccompanying drawings there is shown for purposes of illustration oneform which the invention may assume in practice.

In these drawings: Fig. 1 is a vertical sectional view, withparts inelevation, illustrating a portion of a drilling apparatus with which theinventionis associated.

weight of the rod line becomes excessive, the

hydraulic pressure in the feeding'means must be suflicient to remove theexcessive rod line weight from the drill bit. Also it is desirable toobtain a rapid feeding movement of the'drill chuck 1 when the latter ismoved to a new rod line gripping position after the feed has moved itsdistance of travel. Also under certain conditions, it is required thatthe rod line be raised and lowered while being rotated, and here again arelatively rapid rate of chuck advance is necessary for the sake ofefliciency.

An object of this invention improved hydraulic pump system havingimproved controlling means' Another object is to provide an improvedmultiple pump system embodied in the hydraulic feeding means of a rotarycore drill whereby the drill bit is fed and 'controlled in an improvedmanner. A further'object is to provide improved hydraulic operatingmeans for the drill'ch uck associated with the is to provide an fluidsystem for. thefeeding means whereby the chuck may be controlled in animproved manner. Yet another object is to provide animprovedmultiplepum'p system for a rotary drill- 'Fig'. 2 is'an enlargedfragmentary side elevational view of a portion of the drilling apparatusshown in Fig. 1.

Fig. 3 is an enlarged horizontal sectional view taken substantially online 3-3 of Fig. 1.

Fig. 4 is an enlarged detail sectional view show ing a portion of one ofthe fluid supply connection s.

Fig. 5 is an enlarged side elevational view of one of the control valvemechanisms.

1 Fig. 6 is a cross sectional view taken on line 6-6 of Fig. 5.

Fig. 7 is a view similar to Fig. 6, showing the control valve in adifferent position.

Fig. 8 is a cross sectional view taken on line 's-a'or Fig. 5.

Fig. 9 is a view'sim-ilar control valve in a difierentposition.

Fig. 10 is an enlarged side elevational view of the by-pass valvemechanism.

Fig. 11 is a cross sectional view taken on line l|--'-il of'Fig. 10.Fig. 12 is a view similar to Fig. by-pass valve in a different position.I

Fig. 13is a cross sectional view taken on line 13-43 of Fig. '10.

Fig. 14 is a. view similar toFig. 13, showing the by-pass valve in adifferent position.

fluid to the system when rapid operation is desired, as for I rapiddrilling in soft formations, the utilization to Fig. 8, showing the 11,showing the s Fig. 15 is an enlarged side elevational view of Fig. 1'7is a view similar to Fig. 16, showing the feed control valve in adifferent position.

Figs. 18 and 19 are diagrammatic views illustrating the hydraulic fluidsystem.

In this illustrative embodiment of the invention the improved hydraulicfluid system is shown embodied in a rotary drilling apparatus of theheavy duty, oil well drill type generally similar to that disclosed inthe patent to H. C. Johansen, No. 2,114,305, patented April 19, 1938,although it will be evident that various features of the invention maybe incorporated in drilling apparatus of various other types.

The rotary drilling apparatus illustrated herein comprises a verticalframe structure I mounted on a suitable base 2 and supporting atransverse upper frame 3. Secured within heads 4 mounted within theupper portion of the frame structure are vertical hydraulic feedcylinders 5, 5 arranged in parallel relation at the opposite sides ofthe frame structure and containing reciprocable feed pistons 6 havingpiston rods 1 extending downwardly through stuffing boxes 8 arrangedwithin the cylinder heads 4. Formed along the opposite sides of theframe sections I beneath the feed cylinders are vertical guideways 9having mounted therein, for vertical reciprocatory movement, slidingguide shoes II. The lower portions of these sliding guide shoes aresecured, as by screws. II, to a transverse frame I2, the frame I2,together with the sliding guide shoes, forming a sliding crossheadstructure vertically reciprocable along the guideways with respect tothe frame structure I. .As illustrated, the lower ends of the pistonrods I are secured at I3 within the transverse crosshead frame I2, sothat when hydraulic pressure is supplied to the feed cylinders the feedpistons are reciprocated therein, moving vertically therewith thesliding crosshead structure. Journaled in ball bearings I4, within thetransverse crossi head frame I2, is a rotary drive sleeve I5 having acentral opening I6 through which a drill rod ll of the drillingapparatus is adapted to extend.

Keyed to the drive sleeve I5 and arranged be-' tween the ball bearingsI4 is a spur gear I8 meshing with and driven by a spur gear I9 (see Fig.3) likewise joumaled within the transverse crosshead. The gear I9. iskeyed to a vertical drive shaft 2I, the latter having telescopicrelation with a driving element arranged within the transverse upperframe 3, in the manner fully described in the above mentioned Johansenpatent, so that irrespective of the position of the sliding crossheadstructure along its guideways the drive sleeve may be rotated.

Carried by the drive sleeve I5 is a hydraulically operated chuckmechanism comprising vertical cylinders 22 carried by the transversecrosshead frame I2 andcontaining vertically reciprocable pistons 23having their piston rods 24 extending upwardly through stufllng boxes 25carried by the transverse crosshead frame I2. The upper ends of thepiston rode 24 are secured at 26 to a transverse frame 21, the lattersupporting a ball bearing in which is joumaled the cylindrical hub 29.of a rotatable chuck casing 30. Guided within guideways 3I formed withina cylindric enlargement 32 of the drive sleeve I5 are chuck jaws 33adapted to grip the drill rod.

Mounted in the chuck casing are blocks 4, co n I hected by pivoted linksa to the chuck-Jaws so that when hydraulic pressure is supplied to thelower ends of the cylinders 22 the pistons 23 are moved upwardly, movingtherewith the chuck casing, and, through the toggle links, moving thechuck jaws into gripping relation with the drill rod, thereby connectingthe drill rod to the drive sleeve for rotation therewith.

Now referring to the means for supplying liquid under pressure to thechuck jaw operating cylinders 22, it will be noted that vertical pipes31 are secured within the lower portion of the frame portion I, andthese pipes extend upwardly through stumng boxes 33 carried withinmembers 39 which constitute the securing elements for securing the lowerends of the piston rods I to the sliding crosshead frame I2. The pipes31 extend upwardly within the bores 43 in the piston rods I, thesepiston rod bores being of slightly larger diameter than the diameter ofthe pipes, so that the liquid flowing through the pipes is dischargedthrough the upper ends of the pipes into the piston rod bores. Thepiston rod bores communicate at their lower ends through ports 4| withannular chambers 42 formed in the sliding crosshead frame I2. As shownmost clearly in Fig. 3, the annular chamber 42, at the right hand sideof the transverse frame I2, is connected through a pipe 43 and branchpipes 44 to the upper ends of the bores of the cylinders 22 at the uppersides of the pistons 23, while the annular chamber". at the lefthandside of the frame I2, is connected through a pipe 45 and branchpipes 46 to the lower ends of the bores of the cylinders 22 at the lowersides of the pistons 23. When hydraulic pressure is supplied to theright hand supply pipe 31, shown'in Fig. 1, liquid under pressure flowsto the right hand annular chamber 42 and thence through the pipes 43 and44 to the upper ends of the cylinders 22, the pressure acting on theupper surface of the pistons 23 to move the latter downwardly into theposition shown in Fig. 1, thereby to release the chuck jaws from thedrill rod. When.hydraulic pressure is supplied to the left hand supplypipe 31, liquid under pressure flows to the left hand chamber 42 andthence through the pipes 45 and 48 to the lower ends of the cylinders22, the pressure acting on the lower surfaces of the pistons 23 to movethe latter upwardly to connect the chuck jaws with the drill rod. It isaccordingly evidentthat irrespective of the adjusted position of thesliding crosshead structure within its vertical guideways relativeto theframe structure I, hydraulic pressure maybe supplied to the hydraulicchuck operating cylinders 22 through the supply pipes 31 telescopicallyarranged within the tubular feed piston rods I, As the structure of thedrilling apparatus is fully described in the above mentioned Johansenpatent, further description thereof is herein unnecessary.

Now referring to the improved hydraulic fluid system, it will be notedthat a liquid pump 5| is provided, this pump being of the dual capacitytype and preferably having a small capacity side and a large capacityside. This pump may consist of two distinct pumping unitscoupled'together,

one pump unit preferably having a substantially larger capacity than theother. The feature, hereinafter more fully explained, of the provisionof means enabling supply from two sources in parallel when needed, butwith power consumption and heat production minimized, is a feature ofbasic importance. The pump It herein comprises a large capacity unit 5|and a small capacity unit 52, these pump units being driven by essence amotor It. The intake sides oi the pump units 56. A branch conduit 66leads from the conduit.

56 also to the valve mechanism 56 v(see Fig. The valve mechanismsillustrated and now tobe described are to be understood as butillustrative Y of the means which can be utilized to accomplish thedesired functions.

The valve mechanism 59, as shown'in Figs. 5 to 9'in'clusive, comprises avalve casing 6| having a bore 62 containing a rotary control valve 63,the

latter having a suitable manual operating handle. The conduits 58 and 60communicate with the valve bore at longitudinally spaced points, whilecommunicating with the valve bore at points diametrically oppositetromthe conduits 58 and 66, respectively, are conduits 64 and 65. The valveis cut away at the opposite sides of a diametric plane to providepassages 66 and 61. Communicating at diametrically opposite points withthe valve bore, midway between the conduits 58 and 64, are conduits 68and 69 respectively leading, through the connections described withrespect to Fig. 1, to the upper and lower ends of the chuck operatingcylinders 22. The com duit 64 is connected to a return conduit 10, inturn communicating with a liquid discharge conduit ll leading back tothe tank 51. Traversing the valve body is a passage 12 adapted toconnect the conduits 60 and 65. When the valve 63 is in the positionshown in Fig. 7, the supply conduit 56 and the exhaust conduit 64 arecut oi! from the conduits 68 and 66 leading to the chuck operatingcylinders 22, and, as shown in Fig. 9, the conduit 60 is connected bythe passage 12 in the valve with the conduit 65, so that liquid underpressure is conducted through the conduit 65 to a by-pass valvemechanism generally designated 13. When the valve 63 is in the positionshown in Fig. 6, the supply conduit 56 is connected to the lower ends ofthe chuck operating cylinders 22 through the conduit 69, while the upperends of the chuck operating cylinders are connected to exhaust throughthe conduit 64. When the position of, the valve 63 is reversed, theupper ends of the chuck operating cylinders are connected to the liquidsupply while the lower ends of the cylinders are connected to exhaust.Whenever bypassing occurs through the passage I2 in the valve, thesupplyof 1mm to the chuck operating cylinders 22 is always out on.

The by-pass valve mechanism 13 comprises, as shown in Figs. to 14inclusive, a casing 14 having a bore 15 containing a rotary valve 16,the latter having a suitable manual operating handle. The conduit 65communicates with the '55 either with the conduit II 'or the conduit 16.Also traversing the valve body is a passage 63 having a narrow bleedingor metering slot 86 for connecting the conduit "to the exhaust conduit86 whereby the lay-passing of fluid past the valve 16, may be closelyregulated. A conduit 85 connects the discharge side of the small pumpunit 52 with the conduit 11. The conduit 11 leads to a valve mechanism,generall designated 66, for controlling the flow of liquid underpressure to the feed cylinders. I

The feed control valve mechanism 86 as shown in Figs. 15, iii-and 17comprises a casing 81 having a bore 68 containing a rotary valve 69, thelatter having a suitable manual operating handle.

The conduit 1'! communicates with the valve bore, and communicating withthe valve bore, at a diametrically opposite point, is a conduit 90, thelatter being connected to the return conduit H leading back to the tank.Also communicating with the valve bore in the same transverse plane withand located midway between the conduits .11 and 90 are conduits 9| and82 leading respectively to the upper and lower ends of the feed valvebore, as shown in Fig. 11. and a conduit 11 communicates with the valvebore at a diametrically opposite point. Communicating with the valvebore at a point in the same plane with and I TI, and the conduit 18 hasa branch conduit 8.0

communicating with thevalve bore in the same cylinders 5. The valve bodyis traversed by passages '93 and 94, and in the difierent positions ofthe valve the passage 93 is adapted to connect the conduit 92 witheither the supply conduit T1 or the exhaust conduit 90, and the passage94 is adapted to connect the conduit 9| either with the conduit 11or'9ll, so that when liquid under pressure is supplied to one of theconduits 9|, 92 the other conduit is always connected to exhaust.Communicating withthe passage 93 is a bleeding or metering slot 95whereby the flow of liquid under pressure from the bottoms of the feedcylinders may be closely regulated, thereby to enable regulation of therate of forward feed. When the valve 89 is in the position shown inFig.. 1'7, the supply of liquid under pressure through the conduits 9|and 92 to the .opposite ends of the feed cylinders is completely outoif, but the connection 92 from beneath the feed pistons has a.restricted connecticn through the slot 95, the passage 93 and alateralenlargement of the mouth of the passage with which .the exhaust conduit90 connects, with the exhaust conduit 90, sothat during drilling underthe weight of the red line the rate of feed can be controlled by finelyregulating the escape of liquid from beneath the fluid pistons.

The supply conduits 58 and respectively leading from the discharge sidesof the large arid small pump units are connected through relief valves96 and 91 with a conduit 88 leading to the discharge conduit H so thatwhen the pressure in the supply conduits becomes excessive the reliefvalves open automatically to relieve the pressure in the system. Therelief valves 96 and 91 may be set at any appropriate pressures suitableto the particular'conditions encountered, but preferably the reliefvalve 91 for the large pump unit is set at a relatively lower pressure.than the pressure setting 'o'fgther'elief valve 96 for the small pumpunit. This difference in pressure settings of the relief valves isdesirable since at times, in'a drilling apparatus of the characterdisclosed herein, a relatively'high pressure must be available to effectcertain auxiliary drill operating functions. However, such differencesin the pressure settings of the relief valves do not come into effect inthe structure embodying the present transverse planes as the conduit 19(Fig. 13).

The valve 16 has a passage 8| provided with a widened mouth 82 forconnecting the conduit invention, and, therefore, the pressure settingsare of no particular. importance herein. In this instance, thefeedingpressure is-determined by the position of the by-pass valve meansand not by the'relief valve settings. of course, when both pump unitsare discharging to the feed cylinders 5; 5, the maximum pressureavailable is the setting pressure of the relief valve 81 for the largepump unit, as both pump units may by-pass through this relief valve.

From the foregoing it will be evident that the liquid discharged fromthe large pump unit 5| may be conducted, under the control of the valve63, to the operating cylinder 22 of the chuck so that the full volumemay be utilized to apply or release the chuck jaws. When the supply ofliquid under pressureto the chuck operating cylinders 22 is cut oil, asshown in Fig. 7, the liquid flowing in the conduit 58 is lay-passedthrough conduit Gil, passage 12 in the valve and conduit I! to theby-pass valve mechanism 13. When the valve 16 is in the position shownin Fig. 12, the liquid is by-passed through conduit 18 to the returnconduit'leading back to the tank. When the by-pass valve 16 is in theposition shown in Fig. 11, liquid under pressure may flow from conduit65 through the passage ii in the valve to the conduit Tl leading to thefeed control valve mechanism 06. Liquid under pressure is continuouslysupplied from one (herein the small) pump unit through conduit 85 to theconduit I1, and when the valves 63 and 16 are in the positions shown inFigs. 9 and 11 pressure is supplied from the large pump unit to theconduit ll, so that the total available supply of pressure fluid is thatdelivered by the pump units combined. When the feed control valve 89 isin the position shown in Fig. 16, liquid under pressure may flow fromconduit 11 through the valve passage $4 to the conduit 9i leading to thetops of the feed cylinders 5, and the bottoms of the feed cylinders areat that time connected to exhaust through conduit 92, passage $3 in thevalve and conduit 90 leading to the liquid return conduit Ii. When thevalve 89 is rotated to a position so that passage 93 connects conduitsI1 and 82, and passage 94 connects conduits 90 and ll, pressure fluid issupplied to the bottoms of feed cylinders 5 and vented from the tops offeed.

cylinders 5. When the liquid supply from the large pump unit isconnected to the return conduit, liquid under pressure may continue tobe supplied from the small pump unit through conduit 85 to the feedcylinders. The large volume discharge from both pump units is utilizedwhen a rapid rate of feed is desired, while the small volume dischargefrom the small pump unit is used in slow feed during normal drilling;and during the slow feedin operation the discharge side of the largepump unit is connected back to the tank through the return valvemechanism.

The presence of the small capacity pump eliminates the excessivegeneration of heat from the fluid system which occurs when a largevolume of liquid is forced through a loaded by-pass valve for anysubstantial length of time. When the valve 16 is in the position shownin Figs. 12 and 14 the discharges from both the large and small pumpunits are conducted through the return conduit III back to the tank.When the valve I6 is in the position shown in Figs. 11 and 13, liquidunder pressure may be. conducted through conduits 58, 65 and 11 to thefeed control valve 86, so that the feed pistons may be fed upwardly ordownwardly as desired under the control of the valve 88 at a relativelyrapid rate. When the valve I6 is in'its by-passing position shown inFigs. 12 and 14,the wide mouth 82 of the passage 8| permits a limitedamount of adjustment of the valve, thereby to permit bleeding of theoutput from the small pump unit by means of the metering slot 84 towhatever pressure is required. The rate and direction of feed may thenbe determined by the position '0! the feed control valve 89. When theweight of the drill rods is in excess to the pressure required to feedthe drill bit to the work both pump units may be by-passed, and the rateof feed is at that time regulated by metering the flow of liquid fromthe lower ends of the feed cylinders beneath the feed pistons by meansof the metering slot in the four-way valve as heretofore explained.Further, when varying or cavernous formations are encountered by thedrill bit, the "under feed" method of feeding the drill bit may beemployed. and at that time the small pump unit may supply liquid underpressure to the upper ends of the feed cylinders above the feed pistons,and the rate of feed may be controlled, as by regulating the amount ofliquid by-passed.

As a result of this invention, it -will be noted that an improvedcontrolling means is provided in the hydraulic fluid system of a rotarydrilling apparatus whereby the feeding means may be controlled in animproved manner. It will further be evident that by the provision of theimproved controlling means for the hydraulic feeding means, the feedingpressure on the drill bit may be controlled through a relatively widerange. hydraulic controlling means for the drill chuck is associatedwith the fluid system for the feeding means whereby the chuck may becontrolled in an improved manner. It will also be evident that by theprovision of the improved multiple pump system the volume of the liquidsupplied to the system may be varied in accordance with the demand.Other uses and advantages of the invention will be clearly apparent tothose skilled in the art.

While there is in this app cation specifical y described one form whichthe invention may assume in practice, it will be understood that thisform of the same-is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

What I claim as new and desire to Letters Patent is:

secure by 1. In a hydraulically operated apparatus, hy-

draulically operable means for selectivel gripping and releasing a tool,hydraulically operable means for selectively feeding and retracting atool when it is gripped by said first mentioned hydraulically operablemeans. a relatively large capacity pumping unit, a relatively smallcapacity pumping unit. a valve means for selectively rendering one ofsaid pumping units operable to supply fluid to said first mentionedhydrauli- It will also be noted that an improved 2. In dhydraulicallyoperated apparatus, hydraulically operable means for selectivelygripping and releasing a tool, hydraulically operable means forselectively feeding and retracting a tool when it is gripped by saidfirst mentioned hydraulically operable means, a' relatively largecapacity pumping unit, a relatively small capacity pumping unit, valvemeans for selectively rendering said first mentioned pumping unitoperable to supply fluid to said first mentioned hydraulically operablemeans to efi'ect gripping of a tool or to trap fluid in said firstmentioned hydraulically operable means to maintain tool gripping whilerendering the discharge of said first men'- tloned pumping unitavailable for other purposes, means for selectively rendering one orboth of said pumping units operable to supply fluid to said secondmentioned hydraulically operable means, a return line, and meansoperable to connect the discharge from one or both of said pumping unitsfreely to said return line when the same are not supplying fluid to saidsecond men'- tioned hydraulically operable means.

3. In a hydraulically operated apparatus, hydraulically operable meansfor selectively grip; ping and releasing a tool, hydraulically operablemeans for selectively feeding and retracting a tool when it is grippedby said first mentioned hydraulically operable means, a relatively largeca pacity pumping unit, a relatively small capacity pumping unit, valvemeans for selectively rendering one of said pumping units operable tosupply fluid to said first mentioned hydraulically operable means toeffect gripping of a tool or to trap fluid in said first mentionedhydraulically operable means to maintain tool gripping while renderingthe discharge of said pumping unit available for other purposes, meansfor selectively rendering the second or both of said pumplng unitsoperable to supply fluid to said second mentioned hydraulically operablemeans, a return line, and means operable to connect the discharge fromone or' both of said pumping units freely to said return line when thesame are not supplying fluid to said second mentioned hydraulicallyoperable means.

4. In a hydraulically operated apparatus, hydraulically operable meansfor selectively gripping and releasing a tool, hydraulically operablemeans for selectively feeding and retracting a tool when it is grippedby said first mentioned hydraulically operable means, a relatively largecapacity pumping unit, a relatively small capacity pumping unit, valvemeans for selectively rendering said first mentioned pumping unitoperable to supply fluid to said first mentioned hydraulically operablemeans to efiect gripping of a tool or to trap fluid in said firstmentioned hydraulically operable means to maintain tool gripping whilerendering the discharge of sa d first mentioned pumping unit availablefor other purposes, means for selectively rendering the second or bothof said pumping units operable to supply fluid to said second mentionedhydraulically operablemeans, a return line, and mean operable to connectthe discharge from one or both of said pumping units freely to saidreturn line when the same are not supplying fluid to said secondmentioned hydraulically operable means.

5. In a hydraulically operated apparatus, hydraulically operable meansfor selectively gripping and releasing a tool, hydraulically operablemeans for selectively feeding and retracting a tool when it is grippedby said firstmentioned hydraulically operable means, a relatively largecapacity pumping unit, a relatively small capacity pumping unit, valvemeans for selectively render- 7 ing one of said pumping units operableto supply fluid to said first mentioned hydraulically oper-' able means.to eflect gripping. o! a tool or to trap fluid in said first mentionedhydraulically operable means to maintain tool gripping whilerenderingthe discharge of said pumping unit avail- .able for other purposes,means for selectively rendering one or both of said pumping unitsoperable to supply fluid to said second mentioned hydraulically operablemeans, a return line, and means operable to connect the discharge fromone or both of said pumping units freely to said return line when thesame are not supplying fluidto said second mentioned hydraulicallyoperable means, said latter means embodying metering slot means wherebythe discharge from one of said pumping units may be closely regulated.

6. In a hydraulically operated apparatus, hy-

hydraulically operable means to eifect gripping of a tool or to trapfluid in said first mentioned hydraulically operable means to maintaintool gripping while rendering, the discharge of said first mentioned.pumping unit availablefor other purposes, means for selectivelyrendering one or both of said pumping unit operableto supply fluid tosaid second mentioned hydraulically operable means, a return line, andmeans operable to connect the. discharge from one or both of saidpumping units freely to said return line'when the same are not supplyingfluid to said second mentioned hydraulically operable means, said lattermeans embodying metering slot means whereby the discharge from the smallpumping unit may be closely regulated.v

7. In combination, a hydraulically operable device including an elementsubjectable to working pressure on its opposite sides, a pump of smallcapacity, a pump of larger capacity, a valve casing providing a borehaving a connection with said pump of larger capacity, and at oppositesides of said first mentioned connection connections to the oppositesides'of said element or said hydraulically operable device, said valvecasing bore also having a second connection with said larger capacitypump, means providing a connection for said bore with said smallercapacity pump, and a valve movable in said casing and having meansformed thereon toward one end thereof for connecting said firstconnection a selectively with the opposite sides of said element of saidhydraulically operable device and means formed adjacent the other endthereof for establishing or interrupting communication between saidsecond. connection and said means providing a connection with saidsmaller capacity operated means and to said mechanism return line tosaid pumps, and controlling means for fluid flow relative to them fromsaid pumps including means providing three valve receiving bores, threevalves movable in said bores respectively, one in each of said bores,fluid supply conduits leading from said pumps, one fluid supply conduithaving passages leading to two of said bores and another havingcommunication with the third of said bores, passage means for connectingsaid last'mentioned bore with one of the others, the valve in the thirdmentioned bore being movable therein to control said mechanism and theconnection of the third mentioned bore with the one of the others towhich said passage means leads from said third mentioned bore, the valvein the bore to which said last mentioned passage means leads controllingcommunication'between that bore and said third mentioned bore andcommunication between each of said supp y conduits and the return lineto said pumps, and the valve in the other of said bores controlling saidhydraulically operated means.

9. In combination, a hydraulically operable device including an elementsubjectable to working pressure on its opposite sides, a pump of smallcapacity, a pump of larger capacity, a valve casing providing a borehaving a connection with said pump of larger capacity, and at oppositesides of said first mentioned connection connections to the oppositesides of said element of said hydraulically operable device, said valvecasing bore also having a second connection with said largercapacitypump, means providing a connection for said bore with saidsmaller capacity pump, and a valve movable in said casing and havingmeans formed thereon toward one end thereof for connecting said flrstconnection selectively with the opposite sides of said element vidingvalve-receiving bores, valves movably arranged in said boresrespectively, a passage connecting the pump of large discharge capacitywith one of said bores, a second passage connecting the pump of smalldischarge capacity with the other bore, a third passage connecting saidboreswhereby the liquid flowing from the large capacity pump from saidone of said bores flows throughsaid third passage to said other bore,the liquid flowing past the valve in said one of said bores to saidthird passage, and a fourth passage communicating with said secondpassage, and said valve in said other bore controlling the flow ofliquid from said third passage to said fourth passage. 1

11. In a hydraulically operated apparatus, a pump having a smalldischarge capacity, a pump having a larger discharge capacity, meansproviding valve receiving bores, valves movably arthrough said thirdpassage to said other bore, the liquid flowing past the valve in saidone of said bores to said third passage, a fourth passage communicatingwith said second passage, and

said valve in said other bore controlling the flow I of liquid from saidthird passage to said fourth passage, and the liquid from the smallerdischarge capacity pump flowing directly from the second passage to saidfourth passage independently of control of the valve in said other bore.

12. In a hydraulically operated apparatus, a pump having a smalldischarge capacity, a pump having a larger discharge capacity,-meansproviding valve receiving bores, valves movably arranged in said boresrespectively, a passage connecting the pump of large discharge capacitywith one of said bores, a second passage connecting the pump of smalldischarge capacity with the other bore, a third passage connecting saidbores whereby the liquid flowing from the large capacity pump from saidone of said bores flows through said third passage to said other bore,the liquid flowing past the valve in said one of said bores to saidthird passage, a fourth passage communicating with said second passage,

1 and said valve in said other bore controlling the flow of liquid fromsaid third passage to said fourth passage, and the liquid from thesmaller discharge capacity pump flowing directly from the second passageto said fourth passage independently of control of the valve in saidother bore, and a discharge line communicating with said other bore andthe valve in said other bore controlling the connection of said secondpassage with said discharge line.

13. In a hydraulically operated apparatus, a pump having a smalldischarge capacity, a pump having a larger discharge capacity, meansproviding valve receiving bores, valves movably arranged in said boresrespectively, a passage connecting the pump of large discharge capacityranged in said bores respectively, a passage conwith one of said bores,a second passage connecting the pump of small discharge capacity withthe other bore, a third passage connecting said bores whereby the liquidflowing from the large capacity pump from said one of said bores flowsthrough said third passage to said other bore, the liquid flowing pastthe valve in said one of said bores to said third passage, a fourthpassage communicating with said second passage, and

said valve in said other bore controlling the flow of liquid from saidthird passage to said fourth passage, and the liquid from the smallerdischarge capacity pump flowing directly from the second passage to saidfourth passage independently of control of the valve in said other bore,and a discharge line communicating with said other bore and the valve insaid other bore controlling the connection of said second .passage withsaiddischarge line, said valve in said other bore also controlling theconnection of said third passage with said discharge line.

14. In a hydraulically operated apparatus, a pump of small dischargecapacity, a pump of large discharge capacity, means providingvalvereceiving bores, valves arranged in said bores respectively, apassage connecting the pump of large discharge capacity with one of saidbores, a second passage connecting the-pinnp of small discharge capacitywith said other bore, a third passage connecting said bores whereby theliquid valve in said other bore controlling the connection or said thirdpassage with said second passage and with said discharg line, and afourth passage communicating with said one bore and controlled by thevalve in said one bore.

15. In a hydraulically operated apparatus, a pump of small dischargecapacity, a pump of large discharge capacity, means providingvalvereceiving bores, valves arranged in said bores respectively, apassage connecting the pump of large discharge capacity with one of saidbores, a second passage connecting the pump of small discharge capacitywith said other bore, a third passage connecting said bores whereby theliquid valve in said other bor controlling the connection of said thirdpassage with said second passage and with said discharge line, and afourth passage communicating with said one bore and controlled by thevalve in said one bore, said 10 valve in said other bore alsocontrolling the connection of said second passage with said dischargeline.

HARRY H. VANDERZEE.

CERTIFICATE OF CORRECTION Patent No. 2,522,759. June 22, 1945.

HARRY H. VANDERZEE.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 68, for rode read -rods page 14., second column, line60,

before "valve" strike out "a"; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to therecord of the case in the Patent Office. I

Signed and sealed this 25rd day of November, A. D. 19143.

. Henry 'Van Arsdale, (Seal) Acting Commissioner of Patents.

